In order to prevent derailment of a rolling stock when a lateral load is applied to the rolling stock due to a natural disaster such as earthquake and gust, a guard angle is provided along the inside of a rail. However, in case the rolling stock is unfortunately derailed over the guard angle, there has been proposed a device which guides the rolling stock so that the rolling stock runs on a ballast with sleepers or a roadbed. The device is provided with a guard angle provided along the inside of a rail and a stopper projecting downward at a position more inside than wheels of a truck, and the stopper is in slidable contact with the inside surface of the guard angle in the derailment to restrict a lateral motion of the truck (for example, see Patent Document 1).